Recently, there has been an increased demand to reduce the amount of carbon dioxide in order to protect the environment. In the automobile industry, electric vehicles (EV) and hybrid electric vehicles (HEV) have been introduced to reduce the amount of carbon dioxide. A secondary battery for powering the motors of the electric and hybrid vehicles has been developed. Japanese Laid-Open Patent Publication No. 2001-236946 discloses a stacked-type bipolar battery for use as a secondary battery. However, such batteries are limited due to the current density change that occurs. That is, in such batteries, a current density change occurs depending on the correlation between an electrical resistance of the current, which flows along the surface direction in a region corresponding to the battery element in the cathode and anode terminals, and a total electrical resistance of the current that flows along the stacking direction between the cathode and anode terminals. This current density change promotes deterioration of the battery element and thereby facilitates the battery's degradation and reduces its durability.